Means for absorbing relief gases from sulphite pulp digesters



J 1946. J. D. JENSSEN MEANS FOR. ABSORBING' RELIEF GASES FROM SULPHITEPULP DIGESTERS Fil'ed June 17, 1944 2 Sheets-Sheet l INVEN TOSZ I XM K?ATToizN 0/ MEANS FOR ABSORBING RELIEF GASES FROM SULPHITE PULP DIGESTERSFiled June 17, 1944 2 Sheets-Sheet 2 I 3 M' 52 #2 LL- E i N l -1 l lINVENTOP.

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Awmzmavs Patented June 25 1946 MEANS FOR ABSORBING RELIEF GASES FROMSULPHITE PULP DIGESTERS Jacob Darre J enssen, New York, N. Y., assignorto York, N. Y.

Jenssen Company, Incorporated, New

Application June 17, 1944, Serial No. 540,878 In Canada March 12,- 1943'1 Claim. 1

The invention relates to means for absorbing relief gases from sulphitepulp digesters as described in the present specification and illustratedin the accompanying drawings that form a part of the same. I a

The invention consists of introducing a means between the digesters andthe acid system for controlling the volume of gas to the system aspointed out broadly andspecifically in the claims for novelty followinga description containing an explanation in detail of the acceptableforms of the invention.

The objects of the invention are to mimimize the fluctuation of thevolume of gas, such fluctuation occurring during the cooking period forthe sulphite pulp with bisulphite acid which ordinarily results in aneven absorption of the gas in the acid from the acid system; to, ensureconstant flow of gas to the acidsystem; to eilect uniform operation ofthe acid system; to decrease the loss of SO: in the gas relieving theacid system; to increase the capacity of the acid system; to devise anapproximate even absorption of the relief gases; and generally toprovide means for tontrolling the volume of gas for even orapproximately even distribution to the system.

In the drawings:

Figure 1 is a diagrammatic view of the system.

Figure 2 is a modification of the system as illustrated in Figure 1.

Like numerals of reference indicate correspending parts in the variousfigures. Referring to the drawings, the digester which is adapted tocontain the wood chips, etc., is indicated by the numeral '0 and has adirect pipe connection ii to the cooler i2, as well as a direct pipeconnection it to the hot acid tank 14, the hot acid tank l4 having thereturned pipe connection L5 to the pipe'connection Ii which leads to thecooler i2. v

The cooler i2 is connected to the pressure absorption tower i8 by thepipe l7 this pressure absorption tower being packed with inert material,the absorption'tower I6 is provided with two outlets, one approximatelyadjacent to the top of the tower and the other being, approximately atthe bottom thereof, in the former case the outlet is provided with apipe connection 18 which leads into the gas holder i9 and in the lattercase the outlet is provided with a pipe connection 20 leading into theacid storage tank 2i this pipe connection 20 being controlled by meansof a valve 22. I

Theacid storage tank is provided with two outlets, one outlet having areturned pipe conw 2" nection 23 leading back into the lower portion 'ofthe pressure absorption tower IS, the pump M being connected to the pipe23 to facilitate the recirculation of a certain amountof the acid thatis in the storage tank 2! in order to absorb more $02 in the acid. Theother outlet of the acid storage tank is connected by a vent pipe 25 tothe pipe 26 which connects the gas holder 19 to the low pressureabsorption tower 21, this pipe 28 is provided with reducing valves 28and 29, as well as, the flow control 30 through which the gases in thegas holder will flow before it reachesthe reducing valves. The lowpressure absorption tower is provided with a packing of inert material.

' In order that the pressure in the pressure gas holder l9 shall bemaintained at an approximately predetermined limit and not to exceed thelimited pressure desired, an automatic back pressure valve Si isintroduced andv connected through the pipe 32 to the pipe 26, the pipe32' emanating from the gas holder 89.

The by-pass pipe 33 is connected to the pipe 34 leading from the sulphurdioxide plant 35. The pipe 34 is connected tothe bisulphite acid makingsystem 36, the latter being provided with the usual water pipe 31 toallow water to enter for acid making and the acid from the bisulphitesystem 36 is pumped through the pump 38.

through the pipe 39 to the low pressure absorption tower 21, flowsthrough the pipe to to the pipe 33, while the acid from the absorptiontower 2i is pumped through the pump M, through the pipe 42 to thepressure absorption tower IS in themodifled system. If it is not desiredtouse a pressure absorption tower, a' wet seal gas holder 43 is'used andthe cooler i2 is connected by a pipe I! to the acid storage tank 2! andthe acid storage tank is in turn connected by pipe 25 to the wetsealsgas holder 63, and the gas from the gas holder is is fed throughthe pipe as to the low pressure absorption tower 21 and the rest of thesystem as hereinabove described is included in the modification. K

It is of course understood that where no other acid tank is providedfor; both the high pressure relief and the low pressure for the digesterare connected to the high pressure absorption tower and if the pressureabsorption tower is omitted and the relief gases are partly absorbed inthe storage tank, the wet seal gas holder as hereinabove described maybe introduced' in the vent pipe between the storage tank and the lowpressure absorption tower in order to obtain an even flow oi gas. I

ascaees During the cooking of sulphite pulp with bisulphite acid, aconsiderable amount of 80: gas is being relieved from the digesterduring the cooking of the wood. The amount of gas so relieved fluctuatesduring the cooking period and results in an uneven absorption of thisgas in the acid from the acid system. By introducing a gas holderbetween the relief pipe from the digesters and the acid system thefluctuations in the volume of gas may be eliminated so that there willbe a constant volume of gas to the acid system. From an operating pointor view this is very important. It will result in a uniform operation ofthe acid system and also increase the capacity of the acid system.

In order to limit the size of the gas holder, an absorption tower, whichmay operate at a predetermined pressure, will accomplish this purpose.It is a well known fact that absorption of S0: in a, liquid is in directproportion to the pressure under which-absorption takes place. Theresult will be that a much larger proportion of the S03 gas thanhitherto has been possible will be absorbed in the acid at this point,This, of course, means that a smaller gas holder will be required.

In order to absorb the SO: still present in the gas holder, 9. lowpressure absorption tower may be introduced, with the result thatpractically all t S0: gas relieved from the digester has been ab--sorbed in the acid from the acid mtem. an important feature for thecontrol of the eel especially in the summer when the temperature of thewater for acid making is high.-

I claim:

In means for absorbing relief Bases from sulphite pulp digesters, adigester having iced lines to a cooler anda hot acid tank respectively,a return pipe connection from the hot acid tank to the feed line betweenthe disaster and the cooler, a feed line from the cooler to a pressureabsorption tower, the latter having a feed line to a gas holder, an acidstorage tank having a feed conthe gas holder and to the low pressureabsorp tion tower, and a bisulphite acid making system connected to saidsulphur dioxide plant and to the low pressure absorption tower.

JACOB DARRE JENSSEN.

